Field of the Invention
The present invention relates to an image blur correction apparatus, a control method, an imaging apparatus, and a lens apparatus.
Description of the Related Art
Panning is one imaging technique for expressing a feeling of dynamism in a subject, and is a technique in which a shutter speed is set to low, and imaging is performed while a user causes a camera to follow the movement of a subject that is moving, for example, in a horizontal direction.
Panning is considered to be a difficult imaging technique for beginners, for two reasons. The first reason is that it is difficult to perform imaging while following with the camera without there being deviation between the subject and the camera. When there is a deviation between the subject and the camera, subject shake occurs. The second reason is that the user does not know an optimum setting value for the shutter speed. When the shutter speed is set to low, since an amount of flow in the background increases, a feeling of dynamism in the subject is obtained, but hand shake and subject shake are likely to occur.
In order to increase a probability of success of panning, a function of supporting panning (hereinafter referred to as panning assist) is known. As an example of panning assist, a function of detecting a deviation between a subject and a camera and correcting subject shake according to the deviation in an optical correction system (hereinafter referred to as a first assist function) may be provided. In addition, a function of a camera automatically setting a shutter speed for panning (hereinafter referred to as a second assist function) may be provided. In Japanese Patent Laid-Open No. 2006-317848, an imaging apparatus in which a difference between a speed of a subject and a speed at which a camera is moved is detected for a first assist function and an amount of deviation corresponding to the difference is corrected by a hand shake correction function is disclosed.
In the imaging apparatus disclosed in Japanese Patent Laid-Open No. 2006-317848, when a difference between a speed of a subject and a speed at which a camera is moved is detected, a motion vector and an angular velocity are used. A vector corresponding to the subject (hereinafter referred to as a subject vector) is detected from the vector detected as the motion vector, and a deviation between the subject and the camera is detected.
However, since the angular velocity sensor includes an inherent offset component, a calculation error occurs due to the offset component. In addition, when a movement amount on an image plane (hereinafter referred to as amount of movement on an image plane) is calculated in order to compare the angular velocity with the vector, division by a frame rate is performed. When the offset component is superimposed on an output of the angular velocity sensor and the frame rate in a low luminance imaging scene is low, a calculation error of the amount of movement on an image plane increases. As a result, the subject vector may be erroneously detected.